The capacitor has substantially shrunk in recent history. Currently, tape casting and related technologies are utilized for the manufacture of multilayer capacitors. There is interest in exploring thin film approaches to creating multilayer capacitors. Ceramic dielectric thin films are commonly formed by a broad range of deposition techniques, such as chemical solution deposition (CSD), evaporation, sputtering, physical vapor deposition and chemical vapor deposition. In order to achieve the requisite dielectric structure, each technique typically requires either a high-temperature deposition or a high-temperature anneal.
Prior art methods of forming a specific structure such as a dielectric that has patterned micron or sub-micron features include irradiative lithographic methods such as photolithography, electron-beam lithography, and x-ray lithography.
Photolithography entails forming a negative or positive resist (photoresist) onto the exposed surface of a substrate. The resist is irradiated in a predetermined pattern, and irradiated (positive resist) or non irradiated (negative resist) portions of the resist are washed from the surface to produce a predetermined pattern of resist on the surface of the substrate. This is followed by one or more procedures. An example of such a procedure entails use of the resist as a mask in an etching process in which areas of the material not covered by resist are chemically removed, followed by removal of resist to expose a predetermined pattern of the conducting, insulating, or semiconducting material on the substrate.
Tape casting also has been used to form features which are micron sized in thickness, but which require an additional technique to enable lateral patterning of the electrodes. Tape-casting enables the formation of layers which have a thickness of 0.8 μm. It is uncertain, however, as to whether tape casting can achieve films which have thicknesses of less than 0.2 μm. Electrode patterns are typically created, at present, by screen printing on the electrode ink. This process typically produces comparatively rough edges on the electrodes, which is one factor that leads to the comparatively large margins that are required in typical multilayer capacitors.
Although irradiative lithographic methods may be advantageous for patterning the electrode (and potentially the dielectric) in many circumstances, these methods require sophisticated and expensive apparatus to reproduce a particular pattern on a plurality of substrates. Additionally, they generally consume more reactants and produce more by-products. Further, they are relatively time-consuming.
A need exists for methods of fabrication of thin films useful in devices such as multilayer capacitors (MLC) which avoid the disadvantages of the prior art methods.